Conventional ink-jet printers utilize a carriage that carries one or more ink-jet printheads in a scanning motion that is perpendicular to the direction of the printer paper path. The printheads scan the page while ejecting ink droplets to form the desired image. In a page-wide-array printer, a page-wide-array (“PWA”) printhead spans an entire pagewidth (e.g., 8.5 inches) and has many more ink nozzles than the scanning-type printheads. The PWA printhead is fixed on a print bar that is typically oriented orthogonally to the paper path. The page moves relative to the fixed PWA printhead as the printhead prints one or more lines at a time of the desired image.
Ink-jet printers often include stationary ink reservoirs connected to the printheads through tubes. These printers are generally called “off-axis” printers, as the external reservoirs are typically known as “off-axis” ink reservoirs. Many off-axis printers have pressurized ink supplies that enable higher flow rates of supply ink to the printheads. A supply may be pressurized by an external source such as an air pump, or it may be a self-pressurized supply that contains a propellant and remains pressurized at all times. In either case the pressure source is used to pressurize the supply's ink.
Pressurized ink supplies provide significant advantages in transferring ink from the supplies to the printheads in required time limits. However, challenges remain with respect to regulating the pressure and the ink associated with pressurized ink supplies.